The best advice given here for your budget would be the Shimano Spheros.
It can output around 10kg of drag pressure straight out of the box, but as has been mentioned you could consider upgrading the washers.
I would recommend using 50lb braid (not mono) for both jigging and popping...with the setup you are using, this line class would be ideal. All you are sacrificing is diameter (abraision resistance), any higher line class would be overkill for such an outfit (but not totally out of the question).
If you plan to use the same reel for both jigging and popping i would recommend the slower 4.6:1 retreive ratio of the Spheros. Despite being slower, you can still get those poppers moving pretty fast to induce strikes from GTs. The ratio is ideal for jigging.
Good luck!